CN111412103B

CN111412103B - Braking method for runner of impact type hydraulic generator

Info

Publication number: CN111412103B
Application number: CN202010250507.8A
Authority: CN
Inventors: 刘思靓; 马建峰; 施旭明
Original assignee: Zhejiang Fuchunjiang Hydropower Equipment Co ltd
Current assignee: Zhejiang Fuchunjiang Hydropower Equipment Co ltd
Priority date: 2020-04-01
Filing date: 2020-04-01
Publication date: 2021-03-09
Anticipated expiration: 2040-04-01
Also published as: CN111412103A

Abstract

The invention discloses a braking method of an impact type hydraulic generator runner, relates to the technical field of hydraulic generators, and is used for solving the problems of long braking time and low braking efficiency of the hydraulic generator.A water outlet valve of a water outlet pipe and a water inlet valve of a water inlet pipe are controlled firstly, so that the stored water in a machine pit at least accounts for 80% of the volume of the machine pit; water storage in the pit of the stirrer on the back of the blade of the rotating wheel is realized, so that the water storage flows in the same direction as the rotating direction of the rotating wheel; the auxiliary brake turbines in the flowing water storage driving pit, which are close to the side wall, rotate, so that the flowing speed of stored water is reduced, the stored water in the pit forms turbulent flow until the rotating wheel stops rotating, and at the moment, a water outlet valve is opened to empty the stored water in the pit; after the maintenance is finished, the water inlet valve is opened, and the water flow of the water inlet pipe impacts the rotating wheel, so that the rotating wheel rotates, and then the rotor is driven to rotate to generate power. The invention can obviously shorten the braking time of the rotating wheel, thereby improving the overhauling and maintaining efficiency.

Description

Braking method for runner of impact type hydraulic generator

Technical Field

The invention relates to the technical field of hydraulic generators, in particular to a braking method for a runner of an impact type hydraulic generator.

Background

Along with the enhancement of people's energy-concerving and environment-protective consciousness, hydroelectric power as green energy is developing vigorously, in the hydroelectric power generation field, the hydraulic turbine group is key part, it usually includes the stator, rotationally set up the rotor in the stator, can drive rotor pivoted runner, runner wherein is set up in a machine hole, the runner includes middle axis body, set up a plurality of blades on the axis body, the front of blade is the upstream face, the back of blade is the surface of a river, one side in machine hole is equipped with the inlet tube that the opening aimed at the blade upstream face, the lower part in machine hole is equipped with the outlet pipe. When water flow with high water level difference in the reservoir passes through the water inlet pipe to form high-speed water flow and impacts blades of the rotating wheel to face the water surface, the rotating wheel can rotate and drive the rotor to rotate, and then electric energy is generated. The water flow impacting the rotating wheel flows out through a water outlet pipe at the lower part of the machine pit. Because the water head (commonly called water head) of the reservoir is larger and larger, the size and the weight of the rotating wheel are correspondingly larger and larger, and the rotating speed of the rotating wheel is higher and higher, the rotating inertia formed by the rotating wheel during working is larger and larger. When the hydraulic turbine unit breaks down or needs to be shut down for maintenance or repair due to other reasons, water inlet of the water inlet pipe needs to be cut off, and meanwhile, the rotating wheel and the rotor are waited to decelerate gradually until the hydraulic turbine unit is shut down, so that maintenance personnel can enter a machine pit to conduct maintenance or repair work.

It will be appreciated that under normal conditions, the very large moment of inertia of the rotor and hence the rotor will take a long time (perhaps 30-40 minutes) to come to a complete shutdown, thereby compromising the speed and efficiency of service or maintenance. Although there are many technical solutions in the prior art for braking a rotor, such as a braking system of an automobile. However, unlike the applicable scenario of the existing braking system, the rotor and the associated rotor have great moment of inertia and inertia, and the blades on the rotor are thin shell members forged by stainless steel and welded with the shaft body, so that the rotor is difficult to bear great braking force, and the cost of the rotor is very high, and once the blades are damaged, serious loss is caused. Therefore, some existing emergency braking systems are not suitable for braking the rotating wheel, and the rotor cannot be provided with a corresponding braking structure for braking because the rotor is arranged in the stator. More times, people can only wait for the rotating wheel with patience and the rotor stops by themselves under the action of friction force with the rotating shaft of the rotor, so that the efficiency of overhauling and maintaining is not improved. In particular, the shutdown time is long, so that the safety risk of the auxiliary system of the unit is caused, and particularly, once the bearing oil supply system is interrupted, a serious bearing burning accident occurs, namely, the power generation time and the power generation amount are reduced, so that the normal operation of a power grid is influenced.

Disclosure of Invention

The invention aims to solve the problems of long braking time, high safety risk, low efficiency and influence on the normal operation of a power grid in the conventional braking mode of the hydraulic generator runner, and provides a braking method of the impact hydraulic generator runner, which can obviously shorten the braking time of the runner, improve the safety and reliability of a unit, improve the maintenance efficiency and be beneficial to the normal operation of the power grid.

In order to achieve the purpose, the invention adopts the following technical scheme:

a braking method for a runner of an impact type hydraulic generator comprises the following steps:

a. firstly, controlling a water outlet valve of a water outlet pipe at the lower part of a machine pit for accommodating a rotating wheel and a water inlet valve of a water inlet pipe of the machine pit to ensure that the stored water in the machine pit at least accounts for 80% of the volume of the machine pit;

b. the rotating wheel rotating by means of inertia forms a speed difference with the stored water in the machine pit, the blades of the rotating wheel are back to the water surface to stir the stored water in the machine pit, and the rotating wheel transfers energy to the stored water in the machine pit, so that the stored water flows in the same direction as the rotating direction of the rotating wheel;

c. the auxiliary brake turbines in the flowing water storage driving pit, which are close to the side wall, rotate, so that the flowing speed of stored water is reduced, the stored water in the pit forms turbulent flow until the rotating wheel stops rotating, and at the moment, a water outlet valve is opened to empty the stored water in the pit;

d. after the maintenance is finished, the water inlet valve is opened, and the water flow of the water inlet pipe impacts the rotating wheel, so that the rotating wheel rotates, and then the rotor is driven to rotate to generate power.

It is known that the braking system of the existing rotating mechanism usually applies a braking torque to the rotating member (mainly the rotating shaft), but the rotating wheel and the rotor of the large hydraulic turbine set have large mass and high rotating speed, and accordingly, the rotating inertia is very large, and if the braking torque is applied to the shaft body of the rotating wheel, the radius is small, so that the overall braking torque is limited under a certain braking friction force, and the rotating wheel and the rotor are difficult to be quickly braked. In addition, the blades of the runner are thin shell parts formed by forging stainless steel, the upstream surfaces of the thin shell parts are concave, and the back surfaces of the thin shell parts are convex outwards, so the thin shell parts are commonly called as buckets. The water bucket is connected with the shaft body in the middle through a welding process after being machined and molded, and when power generation is needed, high-speed large-flow water flows out of the water inlet pipe and sequentially impacts the upstream surface of each blade, so that the rotating wheel is driven to rotate at a high speed. That is, the operating torque applied to the runner by the water flow is uniformly applied to the upstream surface of each blade by the water flow, and thus, although the overall operating torque is large, the acting force applied to each blade of the runner is relatively gentle. That is, if we apply a great braking force directly to the blade in a short time at the time of braking, the blade may be damaged.

Therefore, when the rotating wheel needs to be braked to stop the machine for maintenance, the invention creatively controls the water outlet valve of the water outlet pipe and the water inlet valve of the water inlet pipe to ensure that the stored water in the machine pit quickly rises to be not less than 80 percent of the volume of the machine pit. At this time, the rotor which continues to rotate by inertia is entirely "buried" in the accumulated water, and the accumulated water with a large volume generates soft and large braking resistance on the blades of the runner to release energy. Particularly, all the blades are subjected to braking resistance at the same time, so that the braking torque can be greatly improved to stop the rotating wheel in the shortest time, the blades are uniformly stressed to the maximum extent, and the blades are prevented from being damaged due to concentrated stress or overlarge stress of the blades.

Furthermore, a plurality of auxiliary braking turbines are arranged in the machine pit close to the side wall. When the runner stirs the retaining in the machine pit to make the retaining form with the rotation direction of runner unanimity, but the velocity of flow is less than the flow of runner, the supplementary braking turbine rotation in the drive machine pit of flowing retaining on the one hand, thereby release and transmit the kinetic energy of retaining to the turbine, on the other hand, when each turbine rotated, can make the retaining that originally flows towards a direction in the machine pit form local original place and rotate, and then make the retaining in the machine pit form high turbulent flow, with furthest consume the energy that transmits to retaining by the runner.

It can be understood that when the rotating wheel stops rotating, the water storage in the machine pit can be emptied by opening the water outlet valve, and the hydraulic turbine set can be repaired and maintained.

In addition, when the water storage in the machine pit accounts for at least 80% of the volume of the machine pit, the rotating wheel can be ensured to be buried in the water storage, the water flow of the water inlet pipe is effectively prevented from directly impacting the blades of the rotating wheel, and the sufficient water quantity in the machine pit can be ensured to fully absorb the energy of the rotating wheel.

Preferably, a reversing cover capable of changing the flow direction of the water flow of the water inlet pipe is arranged at a water spray port connected with the machine pit, in the step a, the water outlet valve of the water outlet pipe is closed, when the stored water in the machine pit accounts for 70% -80% of the volume of the machine pit, the water inlet valve of the water inlet pipe is closed, then the water flow direction of the water inlet pipe is changed through the reversing cover, the water flow of the water inlet pipe faces the back surface of the blade, and then the water outlet valve of the water outlet pipe is partially opened, so that the stored water in the machine pit at least accounts for 80% of the.

The invention arranges the reversing cover which can change the flow direction of the water flow of the water inlet pipe at the outlet of the water inlet pipe, so that when power generation is needed, the water flow flowing out of the water inlet pipe impacts the upstream surface of the blade by the reversing cover, and the rotor is driven to rotate by the rotating wheel so as to generate power. When the machine needs to be stopped for maintenance, the water outlet valve of the water outlet pipe is closed firstly, so that the stored water in the machine pit can quickly rise to 70% -80% of the volume of the machine pit, and huge resistance is formed on the rotation of the rotating wheel. Then the water flow direction of the water inlet pipe is changed through the reversing cover, so that the water flow of the water inlet pipe faces to the back surface of the blade, and the impact force of the water flow of the water inlet pipe is utilized to generate braking resistance on the rotating wheel.

It can be understood that, when the water flow of the water inlet pipe faces the back water surface of the blade, the water storage in the machine pit rises to 70% -80% of the volume of the machine pit, that is, the rotor at the moment is buried in the water storage, therefore, the water flow of the water inlet pipe does not directly impact on the back water surface of the blade but impacts on the water storage rotating along with the rotating wheel, on one hand, the impact force on the blade can be greatly buffered, on the other hand, the flow speed of the water storage can be greatly reduced, the flow speed difference between the water storage and the rotating wheel is increased, the water storage becomes the braking resistance of the rotating wheel, and the rapid braking and stopping of the rotating wheel are facilitated.

It should be noted that, before the water flow direction of the water inlet pipe is changed by the reversing cover, the water inlet valve of the water inlet pipe is firstly closed, so that the water flow of the water inlet pipe is reduced, and the adjustment of the reversing cover is facilitated.

Particularly, after the water flow direction of the water inlet pipe is changed through the reversing cover, the water outlet valve of the water outlet pipe is partially opened so as to discharge part of stored water rotating along with the rotating wheel in the machine pit in time, and the stored water in the machine pit is kept at least 80 percent of the volume of the machine pit by reasonably controlling the opening and closing sizes of the water inlet valve and the water outlet valve. That is to say, the impounded water in the machine pit can be continuously replaced by the water flow flowing in from the water inlet pipe, and the impounded water flowing in newly can form the flow opposite to the rotating direction of the rotating wheel, so that the impounded water in the machine pit can always keep the braking effect on the rotating wheel. That is, the total water intake in the reservoir can be increased as much as possible by the uninterrupted water intake to absorb the energy of the runner.

Preferably, an overflow hole is provided at an upper portion of the pit, and when a water level of the water stored in the pit reaches a position of the overflow hole, the water can be discharged to the outside through the overflow hole.

The overflow hole is convenient for the redundant stored water in the machine pit to be discharged outwards, thereby being convenient for the control of the water inlet valve and the water outlet valve. Particularly, when the water inlet amount is larger than the water outlet amount, so that the water level of the water stored in the machine pit continuously rises and is discharged from the overflow hole to the outside, the water stored in the machine pit which is rotated is respectively shunted to the outside through the overflow hole at the upper part and the water outlet pipe at the lower part, and then the water flowing in from the water inlet pipe supplements the discharged stored water and absorbs the kinetic energy of the rotating wheel again. That is, by separately discharging water from the upper and lower parts, the accumulated water in the pit can be kept in a low-speed flowing state to the maximum extent, and the braking resistance to the runner can be increased.

Preferably, an annular water guide wall is arranged in the machine pit, the annular water guide wall encloses a central braking water area, an annular braking water area is formed between the water guide wall and the inner side wall of the machine pit, the axis of the rotating wheel is vertically positioned in the central braking water area, a plurality of water guide openings are arranged on the water guide wall at equal intervals, and the auxiliary braking turbine is arranged in the annular braking water area corresponding to the water guide openings.

The scheme is suitable for a vertical water turbine unit, wherein the axis of the runner is vertically positioned in a central braking water area, and the annular water guide wall encloses a central braking water area and an annular braking water area positioned between the water guide wall and the inner side wall of the pit. When the machine needs to be stopped for maintenance, the machine pit stores water, and the rotating wheel drives the center to brake the water stored in the water area to rotate so as to release the inertia and the kinetic energy of the rotating wheel. Because the volume of the central braking water area is relatively small, the water stored in the central braking water area can form basically the same flow speed by the rotating wheel, and the energy of the rotating wheel can be absorbed by the stored water as much as possible.

In addition, the stored water rotating in the central braking water area can enter the annular braking water area through the water guide opening in the water guide wall, so that the auxiliary braking turbine arranged in the annular braking water area corresponding to the water guide opening is effectively driven to rotate, the energy of the rotating stored water in the central braking water area is released, the rotating speed of the stored water is reduced, and the high turbulence is formed by the stored water in the annular braking water area through the rotating auxiliary braking turbine.

According to the law of conservation of energy, most of inertial rotation energy of the rotating wheel is converted into kinetic energy stored in the machine pit and rotation energy for assisting in braking the turbine. Accordingly, as the flow rate of the impounded water is higher, it absorbs more energy, and as the rotational speed of the auxiliary brake turbine is higher, it absorbs more energy. Therefore, under the same machine pit volume, the distance between the annular water guide wall and the runner blade can be properly reduced, on one hand, the runner can fully drive the stored water in the central braking water area to rotate at a higher speed so as to release energy to the maximum extent, and on the other hand, the water entering the annular braking water area through the water guide opening has higher flow speed and kinetic energy so as to drive the auxiliary braking turbine to rotate at a higher speed so as to release the kinetic energy of running water. That is, in the central braking water area, the energy of the runner is absorbed mainly through the impoundment of water, and the impoundment of the runner is mainly laminar flow; in the annular braking water area, the kinetic energy of the impounded water is absorbed mainly through the auxiliary braking turbine, and the impounded water is mainly turbulent flow. When the opening of the water outlet pipe is arranged at the bottom of the machine pit and close to the central position, laminar water storage can be timely discharged from the central braking water area, turbulent water storage in the annular braking water area can be timely discharged from the overflow hole arranged on the side wall of the machine pit, and therefore water flowing into the machine pit through the water inlet pipe can be supplemented into the central braking water area and the central braking water area, and the water can be discharged outwards after the energy of the rotating wheel is absorbed to the maximum extent.

Preferably, the central line of the water guide opening is tangent to the outer edge of the runner, so that the water guide opening is obliquely arranged on the water guide wall.

The water guide port is obliquely arranged on the water guide wall, and the center line of the water guide port is tangent to the outer edge of the rotating wheel. In this way, the water flow tangentially flowing out along the edge of the runner can rapidly enter the water guide opening to push the auxiliary braking turbine to rotate so as to transfer the energy of the water flow to the auxiliary braking turbine. In addition, the water guide walls are in a sawtooth shape due to the water guide openings which are obliquely arranged, so that the obstruction to the water flow in the central braking water area can be remarkably increased, and the kinetic energy of the water flow can be reduced. That is to say, the water flow flowing in the central braking water area drives the water in the water guide opening on one hand, so that the water in the water guide opening flows to form a certain water flow and drives the auxiliary braking turbine to rotate, and on the other hand, the water flow decelerated after the kinetic energy is released is driven by the runner and the water flow driven by the blades to increase the speed again, so that the continuous transfer and release of the energy are realized.

Preferably, the water inlet pipe comprises a main pipe communicated with the reservoir, a power generation branch pipe and a brake branch pipe which are connected to the main pipe in parallel, the main pipe, the power generation branch pipe and the brake branch pipe are connected in a Y shape, so that a third connection point is formed between the power generation branch pipe and the brake branch pipe, a second connection point is formed between the main pipe and the brake branch pipe, a first connection point is formed between the main pipe and the power generation branch pipe, the power generation branch pipe and the brake branch pipe respectively form water spray nozzles on the machine pit, wherein the water spray nozzles of the power generation branch pipe face the upstream surface of the blades, the water spray nozzles of the brake branch pipe face the downstream surface of the blades, the water inlet valve is arranged on the main pipe, a rotatable steering valve plate is arranged at the third connection point, in the step a, the water outlet valve of the water outlet pipe is firstly closed, then the steering valve plate is rotated, at the moment, the main pipeline is communicated with the brake branch pipeline, and water flow flowing out of the brake branch pipeline forms water storage in the machine pit; in step b, the water flow flowing out of the brake branch pipe enables the water stored in the machine pit to form annular flow opposite to the rotating direction of the rotating wheel.

The water inlet pipe comprises a main pipeline, a power generation branch pipeline and a brake branch pipeline which are connected into a Y shape, and a rotatable steering valve plate is arranged at a third connecting point between the power generation branch pipeline and the brake branch pipeline. When normal electricity generation, the free end of steering valve plate supports and leans on junction second tie point between trunk line and the braking branch pipeline to shutoff braking branch pipeline, the rivers of inlet tube are all through generating electricity branch pipeline entering machine hole in impact runner and be used for the electricity generation this moment. When needing to shut down and overhaul, can close the outlet valve door of outlet pipe earlier to make the pit seal, then rotate and turn to the valve plate, make the free end that turns to the valve plate support and lean on first connecting point, trunk line and braking branch pipeline intercommunication this moment, the rivers that flow from braking branch pipeline form the retaining in the pit fast on the one hand, on the other hand forms the rivers that the rotation opposite direction of a direction and runner, thereby forms the braking to the runner. That is to say, through simple steering valve plate, can conveniently change the direction of the rivers that get into the machine hole, not only can make full use of the rivers of inlet tube and fill the machine hole fast, can form reverse impact braking to the runner simultaneously. Especially, the steering valve plate does not seal the whole main pipeline in the rotating process, but only switches the direction of water flow, so that the rotating steering valve plate does not have great resistance, and the direction of the water flow of the main pipeline can be conveniently adjusted.

Preferably, a brake ring pipe communicated with the brake branch pipe is arranged on the outer side of the machine pit, a plurality of nozzles penetrating through the side wall of the machine pit are arranged on the brake ring pipe and face the back water surface of the blade, and in the step a, water in the brake branch pipe flows out through the nozzles, so that outer annular water flow is formed at the position close to the side wall of the machine pit; in the step b, the runner drives the water storage in the middle of the machine pit to form an inner annular water flow, and the rotation directions of the outer annular water flow and the inner annular water flow are opposite.

The invention sets a brake ring pipe communicated with the brake branch pipe outside the pit, and sets a plurality of nozzles facing to the back surface of the blade on the brake ring pipe. When needing to shut down and overhaul, closing the outlet valve door of outlet pipe earlier to make the machine hole seal, then rotate the diverter valve board, make trunk line and braking branch pipeline intercommunication, the rivers of trunk line can pass through braking branch pipeline and get into in the braking ring pipe, outwards flow out from each nozzle again, form the retaining fast in the machine hole on the one hand, on the other hand forms the rivers that the rotation opposite direction of a direction and runner at the periphery in machine hole, thereby form the braking to the runner. It can be understood that the nozzles are arranged, so that the water yield of the nozzles can be obviously reduced on the premise of ensuring the total water yield of the brake branch pipeline, the impact force of the water flow is uniformly applied to the periphery of the whole machine pit, and the damage of blades caused by the concentrated stress of the rotating wheel is avoided. It should be noted that, the sum of the flow rates of the nozzles is equal to the flow rate of the brake branch pipe through reasonable design, and the water discharge amount of the water outlet pipe and the water inlet amount of the water inlet pipe are kept basically equal by controlling the opening degree of the water outlet valve, so that the water storage in the machine pit can be replaced in time, and the braking time of the rotating wheel is shortened to the maximum extent.

Therefore, the invention has the following beneficial effects: the braking time of the rotating wheel can be obviously shortened, so that the overhauling and maintaining efficiency is improved, and the normal operation of a power grid is facilitated.

Drawings

Fig. 1 is a schematic structural diagram of the horizontal water turbine generator set.

Fig. 2 is a schematic structural diagram of the vertical water turbine generator set.

Fig. 3 is a partial structural schematic view of the water inlet pipe.

FIG. 4 is a schematic view of a connection structure of a diverter valve plate in a water inlet pipe.

Fig. 5 is a schematic structural diagram of a vertical hydroelectric generating set with a brake ring pipe in a machine pit.

Fig. 6 is another schematic structural diagram of the vertical hydroelectric generating set with a braking ring pipe in the machine pit.

In the figure: 1. the water turbine comprises a machine pit 11, an overflow hole 12, a water guide wall 121, a water guide port 13, a central brake water area 14, an annular brake water area 2, a runner 21, a shaft body 22, blades 3, a water inlet pipe 31, a water spray port 32, a reversing cover 33, a main pipe 34, a power generation branch pipe 35, a brake branch pipe 36, a first connecting point 37, a second connecting point 38, a third connecting point 39, a water inlet valve 4, a water outlet pipe 41, a water outlet 42, a water outlet valve 5, an auxiliary brake turbine 6, a steering valve plate 61, a rotating shaft 62, a rotating handle 7, a brake ring pipe 71, a branch pipe 711, a nozzle 8 and a compressed air pipe.

Detailed Description

The invention is further described with reference to the following detailed description and accompanying drawings.

As shown in fig. 1, a braking method for a runner of an impulse type hydraulic generator, wherein the hydraulic generator includes a stator and a rotor (not shown in the figure), the runner 2 is rotatably disposed in a machine pit 1, the runner includes a shaft body 21 coaxial with the rotor and blades 22 disposed on the shaft body, the machine pit is provided with a water jet 31 communicated with a water inlet pipe 3 and a water outlet 41 communicated with a water outlet pipe 4, the water inlet pipe is provided with a water inlet valve 39 for controlling opening and closing, and the water outlet pipe is provided with a water outlet valve 42. When high-pressure high-speed water flow in a water inlet pipe communicated with the reservoir flows out from the water spray ports to impact the water-facing surfaces of the blades, the rotating wheel can be driven to rotate, so that the rotor is driven to rotate to generate electricity, at the moment, the water flow of the water spray ports sequentially impacts the blades of the rotating wheel, the rotating wheel is ensured to continuously rotate to generate electricity, and the water entering the machine pit is discharged outwards through a water outlet pipe at the lower part.

It should be noted that, in the power generation, one side of the rotor blade facing the water jet is referred to as a upstream side, and the other side is referred to as a downstream side. That is, the water stream of the water jet nozzle strikes the upstream surface of the blade to rotate, and the downstream surface of the runner is on the front side in the direction of rotation when the runner rotates.

When the hydraulic generator needs to be overhauled or maintained, the rotating wheel needs to be braked firstly, and the invention is an impact type hydraulic generator rotating wheel braking method, which improves the overhauling efficiency, reduces the downtime and is beneficial to the normal operation of a power grid by braking the rotating wheel quickly.

Specifically, the method comprises the following steps:

a. firstly, controlling a water outlet valve of a water outlet pipe at the lower part of a machine pit for accommodating a rotating wheel and a water inlet valve of a water inlet pipe of the machine pit to ensure that the stored water in the machine pit rises to at least 80 percent of the volume of the machine pit, and then submerging the rotating wheel in the stored water;

b. the rotating wheel rotating by means of inertia forms a speed difference with the stored water in the machine pit, so that the blades of the rotating wheel are back to the water surface to stir the stored water in the machine pit, the rotating wheel transfers energy to the stored water in the machine pit, and the stored water flows in the same direction as the rotating direction of the rotating wheel;

c. the auxiliary braking turbines 5 in the flowing impounded water driving pit close to the side wall rotate so as to reduce the flowing speed of impounded water, and the rotating auxiliary braking turbines enable the impounded water in the pit to form turbulent flow until the runner stops rotating. That is, the runner transfers energy to the impoundment of water in the pit, which transfers the absorbed energy to the auxiliary braking turbine, thereby enabling the runner to brake quickly. At the moment, a water outlet valve is opened to drain the stored water in the machine pit, and an operator can start to overhaul or maintain the rotating wheel, the rotor and the like;

d. after the maintenance is finished, the water inlet valve is opened, and the water flow of the water inlet pipe impacts the rotating wheel, so that the rotating wheel rotates, and then the rotor is driven to rotate to generate power. Of course, the water outlet valve should be opened at the same time so as to discharge the water in the machine pit outwards in time.

It is known that the mass and the rotation speed of the runner and the rotor of a large hydraulic turbine set are high, and accordingly, the moment of inertia is very large, and if the runner is always actuated by applying a braking torque to the shaft body of the runner, the radius of the runner is small, so that the overall braking torque is limited under a certain braking friction force, and the runner and the rotor are difficult to be rapidly braked. In addition, the blades of the runner are thin shell parts formed by forging stainless steel, and the single blade is difficult to bear large braking impact force.

The invention creatively stores water in the machine pit by controlling the water outlet valve of the water outlet pipe and the water inlet valve of the water inlet pipe, so that the whole rotor which continuously rotates by means of inertia is buried in the stored water, and the stored water with huge volume generates soft and huge braking resistance to the blades of the rotating wheel. Particularly, all the blades are subjected to braking resistance at the same time, so that the braking torque can be greatly improved to stop the rotating wheel in the shortest time, the blades are uniformly stressed to the maximum extent, and the blades are prevented from being damaged due to concentrated stress or overlarge stress of the blades.

Because the auxiliary braking turbines are arranged in the machine pit close to the side wall. When the runner agitates the impounded water in the sump, the impounded water will flow in a direction consistent with the direction of rotation of the runner and close to laminar flow, although the velocity of the impounded water will be lower than the linear velocity of the blade edge of the runner. At the moment, the flowing water storage drives the auxiliary braking turbine in the machine pit to rotate, so that the kinetic energy of the stored water is released and transmitted to the turbine, and the flow speed of the stored water is reduced. On the other hand, when each turbine rotates, the stored water which originally flows towards one direction in the machine pit forms local rotation, and further the stored water close to the edge in the machine pit forms high turbulence, the turbulent stored water and the laminar stored water in the middle of the machine pit are mutually blended, and then the flow velocity of the intermediate layer laminar stored water is reduced by passing through the turbulent stored water, so that the energy transferred to the stored water by the runner is consumed to the maximum extent.

It should be noted that, when the impounded water in the pit occupies at least 80% of the volume of the pit, it can be ensured that the runner is "buried" in the impounded water, so as to effectively avoid the water flow of the water inlet pipe directly impacting the blades of the runner, and it can be ensured that the pit has enough water to fully absorb the energy of the runner.

As a preferred scheme, a reversing cover 32 capable of changing the flow direction of the water flow of the water inlet pipe can be rotatably arranged at a water spray opening of the water inlet pipe connected with the machine pit, the reversing cover has two positions, and when the reversing cover is in a first position, the water flow flowing out of the water spray opening is opposite to the upstream surface of one blade of the rotating wheel; when the reversing cover is in the second position, the water flow flowing out of the water jet is opposite to the back surface of the other blade of the runner.

Therefore, when power is generated, the reversing cover is located at the first position, water flow impacts the upstream surface of one blade to drive the rotating wheel to rotate, and the water flow can impact the upstream surface of the blade behind the rotating wheel, so that the rotating wheel continuously rotates to drive the rotor to rotate and generate power. When the maintenance is needed, in the step a, the water outlet valve of the water outlet pipe can be closed firstly to seal the water outlet pipe, and at the moment, the water flowing out of the water spraying port enables the water level in the machine pit to rise rapidly. When the water storage in the machine pit accounts for 70-80% of the volume of the machine pit, the water storage can form huge resistance to the rotation of the rotating wheel. Then we can make the direction changing cover rotate from the first position to the second position to change the water flow direction of the water inlet pipe flowing from the water jet, and make the water flow of the water jet face the back surface of the blade, so as to utilize the impact force of the water flow of the water inlet pipe to generate braking resistance to the rotating wheel to accelerate the braking of the rotating wheel.

Certainly, in order to facilitate the rotation of the reversing cover, the water inlet valve of the water inlet pipe can be firstly closed to reduce the acting force of the water flow of the water spray opening on the reversing cover, and after the reversing cover rotates from the first position to the second position, the braking force generated by the impact force of the water flow of the water inlet pipe on the rotary wheel can be properly controlled. It will be appreciated that in power generation, the water stream from the water jet initially impacts the upstream face of the stationary blade, and in braking, the water stream from the water jet impacts the downstream face of the rotating blade, with the relative velocity difference between the two being much greater than the velocity difference between the water stream and the blade in power generation, and accordingly, the force of the water stream on the blade will be greater at this time. Therefore, the invention creatively controls the water flow of the water jet appropriately to smooth the braking force born by the blade.

Then, the outlet valve of the outlet pipe is partially opened to discharge the flowing water to the pit, and the inlet valve is controlled to make the water jet keep a partial water inlet state, so that the water stored in the pit is maintained at least 80% of the volume of the pit. Therefore, the water stored in the machine pit is continuously replaced by the water flow flowing in from the water spraying opening, and the newly flowing water can form a flow opposite to the rotating direction of the rotating wheel, so that the water stored in the machine pit can always keep the braking effect on the rotating wheel. That is, the total water intake in the reservoir can be increased as much as possible by the uninterrupted water intake to absorb the energy of the runner.

It can be understood that the designed water discharging speed of the water outlet pipe is certainly greater than the designed water inlet speed of the water inlet pipe, so that no water accumulation is generated in the engine pit during power generation. Therefore, after the reversing cover rotates from the first position to the second position and when the stored water in the machine pit accounts for 70% -80% of the volume of the machine pit, the water inlet valve is completely opened, then the water outlet valve is properly controlled, so that the water inlet of the water inlet pipe and the water discharge of the water outlet pipe are kept basically balanced, and meanwhile, the replacement speed of the stored water in the machine pit is increased to the maximum extent, and the braking effect on the rotating wheel is improved as much as possible.

Preferably, in step a, when the outlet valve of the outlet pipe is closed to close the outlet pipe, the reversing cover can be rotated from the first position to the second position to change the direction of the water flow of the inlet pipe from the water jet, so that the water flow of the water jet faces the back surface of the blade, and the impact force of the water flow of the inlet pipe is used to generate braking resistance on the rotating wheel to accelerate the braking of the rotating wheel, and at the same time, the water flowing out of the water jet rapidly raises the water level in the machine pit to 70% -80% of the volume of the machine pit.

Furthermore, an overflow hole 11 communicated with the water outlet pipe can be arranged at the upper part of the machine pit, and when the water level stored in the machine pit reaches the position of the overflow hole, the water can be discharged outwards through the overflow hole, so that the control of the water inlet valve and the water outlet valve is facilitated. Particularly, when the water inlet amount is larger than the water outlet amount, so that the water level of the water stored in the machine pit continuously rises and is discharged from the overflow hole to the outside, the water stored in the machine pit which is rotated is respectively shunted to the outside through the overflow hole at the upper part and the water outlet pipe at the lower part, and then the water flowing in from the water inlet pipe supplements the discharged stored water and absorbs the kinetic energy of the rotating wheel again. That is, by separately discharging water from the upper and lower parts, the accumulated water in the pit can be kept in a low-speed flowing state to the maximum extent, and the braking resistance to the runner can be increased.

It should be noted that the hydraulic turbine unit of the present invention may be a vertical unit in which the rotation axis of the runner is vertically arranged, or a horizontal unit in which the rotation axis of the runner is horizontally arranged.

Furthermore, for the vertical unit, as shown in fig. 2, an annular water guide wall 12 surrounding the runner may be disposed in the pit, a plurality of water guide openings 121 are disposed on the water guide wall at equal intervals, the annular water guide wall encloses a central braking water area 13, and an annular braking water area 14 is formed between the water guide wall and the inner side wall of the pit. At the moment, the axis of the runner is vertically positioned in the middle of the central braking water area, and the auxiliary braking turbine is arranged in the annular braking water area corresponding to the water guide port.

When the machine needs to be stopped for maintenance, the machine pit stores water, and the rotating wheel drives the center to brake the water stored in the water area to rotate so as to release the inertia and the kinetic energy of the rotating wheel. Because the volume of the central braking water area is relatively small, the water stored in the central braking water area can form basically the same flow speed by the rotating wheel, and further the energy of the rotating wheel can be absorbed as much as possible by the water stored in the central braking water area. In addition, the stored water rotating in the central braking water area enters the annular braking water area through the water guide opening in the water guide wall, so that the auxiliary braking turbine arranged in the annular braking water area corresponding to the water guide opening is effectively driven to rotate, the energy of the stored water rotating in the central braking water area is released, the rotating speed of the stored water entering the annular braking water area is reduced, and the rotating auxiliary braking turbine can enable the stored water in the annular braking water area to form high turbulence.

When the impounded water rotating in the central braking water area enters the annular braking water area through the water guide port on the water guide wall, the impounded water can collide with the impounded water forming turbulent flow in the annular braking water area, namely, the water guide port can form great resistance to the impounded water rotating in the central braking water area, and then the rotating wheel is braked.

In particular, the centre line of the water guiding opening is tangent to the outer edge of the blade on the runner, so that the water guiding opening is arranged obliquely on the water guiding wall. In this way, the water flow tangentially flowing out along the edge of the runner blade can rapidly enter the water guide opening to push the auxiliary braking turbine to rotate so as to transfer the energy of the water flow to the auxiliary braking turbine. In addition, the water guide port arranged obliquely enables the water guide wall to be in a sawtooth shape, so that the obstruction to the water flow can be obviously increased, and the kinetic energy of the water flow in the central braking water area can be reduced. That is to say, the water flow flowing in the central braking water area drives the water in the water guide opening on one hand, so that the water in the water guide opening flows to form a certain water flow and drives the auxiliary braking turbine to rotate to release kinetic energy, and on the other hand, the water flow decelerated after the kinetic energy is released between the rotating wheel and the water guide wall is driven by the rotating wheel and the water flow driven by the blades to increase the speed again, so that the continuous transfer and release of energy are realized.

As another preferable scheme, as shown in fig. 1, 3 and 4, the water inlet pipe includes a main pipe 33, one end of the main pipe is communicated with the reservoir, the other end of the main pipe is connected in parallel with a power generation branch pipe 34 and a brake branch pipe 35, the main pipe, the power generation branch pipe and the brake branch pipe are connected in a Y shape, so that a third connection point 38 is formed at the pipe wall connection position of the power generation branch pipe and the brake branch pipe, a second connection point 37 is formed at the pipe wall connection position of the main pipe and the brake branch pipe, and a first connection point 36 is formed at the pipe wall connection position of the main pipe and the power generation branch pipe. Of course, the water spraying ports of the power generation branch pipeline and the brake branch pipeline are respectively formed on the machine pit, the water spraying ports of the power generation branch pipeline face the upstream face of the blade, and the water spraying ports of the brake branch pipeline face the downstream face of the blade. In addition, the water inlet valve is arranged on the main pipeline, the steering valve plate 6 is arranged at the third connecting point, one end of the steering valve plate is rotatably connected to the third connecting point, and the other end of the steering valve plate is a rotatable free end, so that the steering valve plate is also provided with a first position and a second position. When the steering valve plate is in the first position, the free end of the steering valve plate abuts against a second connection point at the connection position between the main pipeline and the brake branch pipeline, so that the brake branch pipeline is blocked, and at the moment, water flow of the water inlet pipe enters the engine pit through the power generation branch pipeline to impact the rotating wheel to generate power. When the steering valve plate is in the second position, the free end of the steering valve plate abuts against the first connecting point, the main pipeline is communicated with the brake branch pipeline at the moment, water flowing out of the brake branch pipeline rapidly forms water storage in the machine pit on the one hand, and water flowing in the direction opposite to the rotating direction of the rotating wheel on the other hand is formed, so that the rotating wheel is braked.

In the step a, the water outlet valve of the water outlet pipe can be closed, then the steering valve plate is rotated, the free end of the steering valve plate abuts against the first connecting point, the main pipeline is communicated with the brake branch pipeline, and water flowing out of the brake branch pipeline forms water storage in the machine pit; in step b, the water flow flowing out of the brake branch pipe enables the water stored in the machine pit to form annular flow opposite to the rotation direction of the rotating wheel, so that the braking is formed on the rotating wheel.

It should be noted that, since the main function of the diverter valve plate is to change the direction of the water flow, that is, the diverter valve plate does not need to have extremely high sealing performance. Therefore, a rotating shaft 61 can be arranged on the outer side of the pipe wall joint of the power generation branch pipe and the brake branch pipe, the rotating shaft extends into the pipe wall and is connected with the steering valve plate, and the outer end of the rotating shaft is provided with a rotating handle 62. When the free end of the steering valve plate abuts against the first or second connecting point, the impact pressure of the water flowing in the pipeline on the steering valve plate can ensure the reliable positioning of the steering valve plate and effectively avoid the free rotation of the steering valve plate.

Furthermore, as shown in fig. 5, a brake ring pipe 7 can be arranged outside the machine pit, one end of the brake ring pipe is communicated with the brake branch pipe, the other end of the brake ring pipe is closed, a plurality of branch pipes 71 are arranged on the brake ring pipe, the branch pipes penetrate through the side wall of the machine pit to form nozzles 711, and the branch pipes are obliquely arranged, so that the nozzles face the back surface of the blades. Therefore, when the machine needs to be stopped for maintenance, the water outlet valve of the water outlet pipe is closed firstly, so that the machine pit is closed, then the steering valve plate is rotated, the main pipe is communicated with the brake branch pipe, and water flow of the main pipe can enter the brake ring pipe through the brake branch pipe and then flows out of each nozzle. In the step a, water in the brake branch pipe flows out through a nozzle, on one hand, water storage is formed in the machine pit quickly, and on the other hand, an outer annular water flow is formed at a position close to the side wall of the machine pit; in the step b, the runner drives the water stored in the middle of the machine pit to form an inner annular water flow, the rotating directions of the outer annular water flow and the inner annular water flow are opposite, and the outer annular water flow can effectively decelerate the inner annular water flow, so that the braking of the runner is increased.

It should be noted that, because a plurality of auxiliary brake turbines are arranged in the pit close to the side wall, when the water in the brake branch pipe flows out through the nozzle and forms an outer annular water flow close to the side wall of the pit, which is opposite to the rotation direction of the inner annular water flow, on one hand, the outer annular water flow can effectively decelerate the inner annular water flow so as to increase the braking on the rotating wheel, and on the other hand, the inner and outer annular water flows can rotate the auxiliary brake turbines so as to form turbulent flow, and particularly, the rotation directions of the adjacent two auxiliary brake turbines close to each other are opposite, so that the water flows stirred by the adjacent two auxiliary brake turbines can interfere with each other to decelerate and consume energy.

The water guide wall is arranged in the machine pit, except for the water guide port on the water guide wall, the central braking water area and the annular braking water area are mutually separated, inner annular water flow taking laminar flow as a main part is formed in the central braking water area, outer annular water flow in opposite directions is formed in the annular braking water area, and the outer annular water flow comprises laminar flow formed by water flow of flowing water of the braking ring pipe and turbulent flow formed by rotation of each auxiliary braking turbine. The inner and outer annular water flows collide at the water guide opening to reduce the flow velocity and counteract the kinetic energy.

As an alternative, as shown in fig. 6, a brake ring pipe may be disposed outside the machine pit, one end of the brake ring pipe is communicated with the compressed air pipe 8 through a control valve, the other end of the brake ring pipe is closed, a plurality of shunt pipes are disposed on the brake ring pipe, the shunt pipes penetrate through the sidewall of the machine pit to form nozzles, and the shunt pipes are disposed in an inclined manner, so that the nozzles face the back surface of the blades.

Like this, when needing to shut down the maintenance, close the outlet valve door of outlet pipe earlier to make the machine hole seal, the intaking of inlet tube makes the retaining in the machine hole rise rapidly to accounting for 80% of machine hole volume at least, and the blade back of the body surface of runner stirs the retaining in the machine hole this moment, and the runner is with the energy transfer for the retaining in the machine hole, makes the retaining form with the unanimous flow of the rotation direction of runner. And then, a control valve is opened, and compressed air enters the machine pit through a flow dividing pipe on the brake ring pipe, so that water stored in the annular brake water area of the machine pit is driven to form outer annular water flow with the direction opposite to that of the inner annular water flow. The inner and outer annular water flows collide at the water guide opening to reduce the flow velocity and counteract the kinetic energy. Because the compressed air acts the braking force on the rotating wheel through the transitional object of the water storage in the annular braking water area, the stress of the blades can be effectively buffered, and the braking energy can be provided through inputting a large amount of compressed air.

Claims

1. A braking method for a runner of an impact type hydraulic generator is characterized by comprising the following steps:

c. the auxiliary brake turbines in the flowing impounded water driving pit close to the side wall rotate, so that the flowing speed of impounded water is reduced, the impounded water in the pit forms turbulent flow until the rotating wheel stops rotating, the water inlet valve is closed at the moment, and the water outlet valve is opened to empty the impounded water in the pit;

2. The method for braking the runner of the impact type hydraulic generator according to claim 1, wherein a reversing cover capable of changing the flow direction of the water flow of the water inlet pipe is arranged at a water spray port where the water inlet pipe is connected with the machine pit, in the step a, the water outlet valve of the water outlet pipe is closed, when the water stored in the machine pit accounts for 70% -80% of the volume of the machine pit, the water inlet valve of the water inlet pipe is closed, then the water flow direction of the water inlet pipe is changed through the reversing cover, so that the water flow of the water inlet pipe faces the back water surface of the blade, and then the water outlet valve of the water outlet pipe is partially opened, so that the water stored in the.

3. The braking method of a runner of an impulse type hydraulic generator as claimed in claim 2, wherein an overflow hole is formed at an upper portion of the pit, and when a water level stored in the pit reaches a position of the overflow hole, the water is discharged to the outside through the overflow hole.

4. The method for braking the runner of the impulse type hydraulic generator as claimed in claim 1, wherein an annular water guide wall is provided in the pit, the annular water guide wall encloses a central braking water area, an annular braking water area is formed between the water guide wall and the inner side wall of the pit, the axis of the runner is vertically located in the central braking water area, a plurality of water guide openings are provided at equal intervals on the water guide wall, and the auxiliary braking turbine is provided at a position corresponding to the water guide openings in the annular braking water area.

5. The method as claimed in claim 4, wherein the center line of the water guiding opening is tangent to the outer edge of the runner, so that the water guiding opening is inclined on the water guiding wall.

6. The method of claim 1, wherein the water inlet pipe comprises a main pipe connected to the reservoir, a power generation branch pipe and a brake branch pipe connected in parallel to the main pipe, the power generation branch pipe and the brake branch pipe are connected in a Y-shape, so that a third connection point is formed between the power generation branch pipe and the brake branch pipe, a second connection point is formed between the main pipe and the brake branch pipe, and a first connection point is formed between the main pipe and the power generation branch pipe, the power generation branch pipe and the brake branch pipe respectively form water nozzles on the machine pit, wherein the water nozzles of the power generation branch pipe face the upstream surface of the blade, the water nozzles of the brake branch pipe face the downstream surface of the blade, the water inlet valve is disposed on the main pipe, a rotatable steering valve plate is disposed at the third connection point, in step a, firstly, closing a water outlet valve of the water outlet pipe, then rotating the steering valve plate to enable the free end of the steering valve plate to abut against the first connecting point, and at the moment, communicating the main pipeline with the brake branch pipeline, and forming water storage in the machine pit by water flow flowing out of the brake branch pipeline; in step b, the water flow flowing out of the brake branch pipe enables the water stored in the machine pit to form annular flow opposite to the rotating direction of the rotating wheel.

7. The method for braking the runner of the impulse type hydraulic generator according to claim 6, wherein a brake ring pipe communicated with the brake branch pipe is provided at the outer side of the machine pit, a plurality of nozzles penetrating the side wall of the machine pit are provided on the brake ring pipe, the nozzles are arranged toward the back surface of the blade, and in the step a, the water in the brake branch pipe flows out through the nozzles, thereby forming an outer annular water flow near the side wall of the machine pit; in the step b, the runner drives the water storage in the middle of the machine pit to form an inner annular water flow, and the rotation directions of the outer annular water flow and the inner annular water flow are opposite.